The present invention generally relates to a method of testing Noise, Vibration, and Harshness characteristics of a gear driven assembly.
In the automotive industry, gear sets are typically tested for Noise, Vibration, and Harshness (NVH) issues to insure satisfactory performance in the vehicle. Current gear testing methods typically test NVH characteristics of a tested gear set in terms of the speed at which the gear set is being operated. In operation within a vehicle, NVH concerns are more accurately a product of the torque that is being transferred across a gear set. Therefore, conventional testing methods which look for NVH issues relative to the speed at which the gear set is being operated do not capture the true performance characteristics of the gear set as the gear set will actually react in operation within a vehicle.
Additionally, to be thorough, both directions of the gear set must be tested. Typically, this involves stopping the test and running the gear set in the opposite direction, thereby causing the gears to engage on the opposite sides of the teeth. This typical stopping of the testing procedure and starting up in the opposite direction adds time to the testing cycle.
Further, as a gear driven assembly is being tested, the system will experience torque losses. Since the torque output will be less than the torque input by the amount of these losses, the gear set is not typically tested at the desired torque levels.
Therefore, there is a need for a method of testing a gear driven assembly which detects NVH characteristics of the gear set in terms of the torque across the gear set rather than the speed at which the gear set is being tested. Further, there is a need for a testing method which will allow both sides of the gear set to be tested in an efficient manner. And finally, there is a need for a testing method which insures that the gear set is being tested at the proper torque levels.